pulsing brakes
 

Hi all.
Can anyone tell me the cause of a pulsing brake lever? I took my 1995 Road king for its annual MOT test a little while ago and the tester failed it on a fluctuating front brake, indicating that either one or both front rotors are warped/worn. Although I couldn't feel anything.
I have fitted two new front rotors, fitted new pads in both callipers and re-shimmed both callipers, just in case. I should say that they are not stock callipers, but 4 pot Harrison billet ones that have been on the bike for years.
I took her for a test ride before booking her in for a re-test and I can feel a slight pulsing through the brake lever. I don't want to ride it now because I fear possibly warping the new rotors.
Anyone had a similar problem?


Thanks in advance for any advice you can give me

Could be warped rotors. But....

You have to let someone else ride you bike????

Don't know about things in the UK. In the US, many states you have to have safety inspections on most any motorized vehicles. A slight pulsation in a brake lever or pedal won't get the vehicle rejected as long as the brakes perform well. Least in Texas anyhow.

Me Too ??? someone else has to ride the bike?

ooohhhh Glad that's not the case here Dang

WP

Oh forgot about cause___ What Dr. Hess says in post #4
Someone else riding your bike really got me

Warped rotor or could have magic dust built up in one spot. See, this magic dust transfers from the pads to the rotors and builds up a layer. That layer is what rubs against the pad. If the magic dust is not uniform on the rotor, that is, too thick on one spot, not there at another, that could cause pulsing as well.

Get the front wheel up in the air and spin it. Check for runout on the disks. Wheel bearing issues? Just a thought. Make sure the disks themselves look flat and uniform too. If everything else looks good, spin it around and take some emery cloth and scuff up both sides of both disks. And, yeah, like ZOMG, someone else rides your bike?

Hi. Thanks for the replys, sorry for the delay in answering but ive been working out of town.
I think I mislead you on the UK mot test. The tester doesn't actually ride the bike, but sits on it while he positions the rear wheel and then the front wheel on a rolling road/rollers whilst applying the brakes, and checks for braking efficiency and also there is a gauge that measures consistency, while the front was on the rollers, and he applied the brakes, the needle on the gauge was bouncing slightly, indicating that the surface of the pads and the rotors weren't consistently touching whilst braking.
But I have changed both rotors, pads and shims so I cant see where the problem lies. But I will certainly check for "magic dust" and go over both discs with emery paper to get rid of any high spots.


Thanks again

After you sand the disks some, you need to apply a new layer of magic dust. This is known as "bedding in the pads." Same as any time you replace rotors on a vehicle: Take it up to speed and panic brake it down to where you are still rolling. Back up to speed again, panic brake down to still rolling, etc. Do that a few times but don't stop when you're doing it, then ride without braking for a while so everything can cool down and you should be OK.

Thank you Dr Hess, advice is much appreciated

No problem. Do make sure it isn't something else outlined above. I would start with a dial indicator and check the runout on the rotors, and with the wheel spinning and someone applying very slight pressure to the brake lever, you might find a tight spot. Hope you get it fixed.

Thanks, me to

Check to see if one of your pistons isnt hung up causing the pad to engage the rotor at an angle causing a slight chatter.